Steel Pipes - Water Flow and Head Loss

Head loss due to friction (ft/100.ft) for water flow in steel pipes schedule 40 - diameter from 1 1/4" to 8"

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The head loss from the table below can be used to calculate major loss in pipes due to friction. Major and minor loss must be summarized for calculating total head loss in the system.

Head Loss due to Friction (ft/100.ft)
Flow (gal/min)	1 1/4"		1 1/2"		2"
Flow (gal/min)	Velocity - v - (ft/s)	Head Loss - h_l - (ft/100 ft)	Velocity - v - (ft/s)	Head Loss - h_l - (ft/100 ft)	Velocity - v - (ft/s)	Head Loss - h_l - (ft/100 ft)
3	0.64	0.21
4	0.86	0.34
5	1.07	0.51
6	1.29	0.71	0.95	0.33	0.57	0.10
7	1.50	0.93	1.10	0.44	0.67	0.13
8	1.72	1.2	1.26	0.56	0.77	0.17
9	1.93	1.5	1.42	0.69	0.86	0.21
10	2.15	1.8	1.58	0.83	0.96	0.25
12	2.57	2.5	1.89	1.16	1.15	0.34
14	3.0	3.3	2.21	1.53	1.34	0.45
16	3.43	4.2	2.52	1.96	1.53	0.58
18	3.86	5.2	2.84	2.42	1.72	0.72
20	4.29	6.3	3.15	2.94	1.91	0.87
22	4.72	7.6	3.47	3.52	2.10	1.03
24	5.15	8.9	3.78	4.14	2.29	1.20
26	5.58	10.7	4.10	4.81	2.49	1.39
28	6.01	11.9	4.41	5.51	2.68	1.60
30	6.44	13.6	4.73	6.24	2.87	1.82
35	7.51	18.5	5.52	8.52	3.35	2.42
40	8.58	23.5	6.30	10.8	3.87	3.10
45	9.65	29.7	7.09	13.7	4.30	3.85
50	10.7	36.0	7.88	16.4	4.78	4.67
55	11.8	43.2	8.67	19.7	5.26	5.59
60	12.9	51.0	9.46	23.2	5.74	6.59
65	13.9	59.6	10.24	27.1	6.21	7.69
70	15.0	68.8	11.03	31.3	6.69	8.86
75	16.1	78.7	11.8	35.8	7.17	10.1
80	17.2	89.2	12.6	40.5	7.65	11.4
85	18.2	100.2	13.4	45.6	8.13	12.8
90	19.3	112.0	14.2	51.0	8.60	14.2
95			15.0	56.5	9.08	15.8
100			15.8	62.2	9.56	17.4
120					11.5	24.7
140					13.4	33.2
160					15.3	43.0
180					17.2	54.1
200					19.1	66.3

Head Loss due to Friction (ft/100.ft)
Flow (gal/min)	2 1/2"		3"		4"
Flow (gal/min)	Velocity - v - (ft/s)	Head Loss - h_l - (ft/100 ft)	Velocity - v - (ft/s)	Head Loss - h_l - (ft/100 ft)	Velocity - v - (ft/s)	Head Loss - h_l - (ft/100 ft)
14	0.94	0.09
16	10.7	0.24
18	1.21	0.30
20	1.34	0.36
22	1.47	0.43	0.95	0.15	0.55	0.04
24	1.61	0.50	1.04	0.18	0.60	0.05
26	1.74	0.58	1.13	0.21	0.66	0.06
28	1.88	0.66	1.22	0.25	0.71	0.07
30	2.01	0.75	1.3	0.26	0.76	0.08
35	2.35	1.0	1.52	0.35	0.88	0.10
40	2.68	1.28	1.74	0.44	1.01	0.12
45	3.02	1.6	1.95	0.55	1.14	0.15
50	3.35	1.94	2.17	0.66	1.26	0.18
55	3.69	2.32	2.39	0.79	1.39	0.21
60	4.02	2.72	2.6	0.92	1.51	0.25
65	4.36	3.16	2.82	1.07	1.64	0.29
70	4.69	3.63	3.04	1.22	1.76	0.33
75	5.03	4.13	3.25	1.39	1.89	0.37
80	5.36	4.66	3.47	1.57	2.02	0.42
85	5.70	5.22	3.69	1.76	2.15	0.47
90	6.03	5.82	3.91	1.96	2.27	0.52
95	6.37	6.45	4.12	2.17	2.40	0.57
100	6.70	7.11	4.34	2.39	2.52	0.62
110	7.37	8.51	4.77	2.86	2.77	0.74
120	8.04	10.0	5.21	3.37	3.02	0.88
130	8.71	11.7	5.64	3.92	3.28	1.02
140	9.38	13.5	6.08	4.51	3.53	1.17
150	10.1	15.4	6.51	5.14	3.78	1.32
160	10.7	17.4	6.94	5.81	4.03	1.49
170	11.4	19.6	7.38	6.53	4.28	1.67
180	12.1	21.9	7.81	7.28	4.54	1.86
190	12.7	24.2	8.25	8.07	4.79	2.06
200	13.4	26.7	8.68	8.90	5.04	2.27
220	14.7	32.2	9.55	10.7	5.54	2.72
240	16.1	38.1	10.4	12.6	6.05	3.21
260	17.4	44.5	11.3	14.7	6.55	3.74
280	18.8	51.3	12.2	16.9	7.06	4.30
300	20.1	58.5	13.0	19.2	7.56	4.89
320			13.9	22.0	8.06	5.51
340			14.8	24.8	8.57	6.19
360			15.6	27.7	9.07	6.92
380			16.5	30.7	9.58	7.68
400			17.4	33.9	10.1	8.47
420					10.6	9.30
440					11.1	10.2
460					11.6	11.1
480					12.1	12.0
500					12.6	13.0
550					13.9	15.7
600					15.1	18.6
650					16.4	21.7
700					17.6	25.0

Head Loss due to Friction (ft/100.ft)
Flow (gal/min)	5"		6"		8"
Flow (gal/min)	Velocity - v - (ft/s)	Head Loss - h_l - (ft/100 ft)	Velocity - v - (ft/s)	Head Loss - h_l - (ft/100 ft)	Velocity - v - (ft/s)	Head Loss - h_l - (ft/100 ft)
40	0.64	0.040	0.44	0.016	0.26	0.004
50	0.80	0.059	0.56	0.024	0.32	0.007
60	0.96	0.081	0.67	0.034	0.39	0.009
70	1.12	0.108	0.78	0.045	0.45	0.012
80	1.28	0.137	0.89	0.056	0.51	0.15
90	1.44	0.169	1.0	0.070	0.58	0.019
100	1.60	0.204	1.11	0.084	0.67	0.022
120	1.92	0.286	1.33	0.118	0.77	0.031
140	2.25	0.380	1.55	0.155	0.90	0.041
160	2.57	0.487	1.78	0.198	1.03	0.052
180	2.89	0.606	2.0	0.246	1.15	0.064
200	3.21	0.736	2.22	0.299	1.28	0.078
220	3.53	0.879	2.44	0.357	1.41	0.093
240	3.85	1.035	2.66	0.419	1.54	0.109
260	4.17	1.20	2.89	0.487	1.67	0.126
280	4.49	1.38	3.11	0.560	1.80	0.144
300	4.81	1.58	3.33	0.637	1.92	0.163
320	5.13	1.78	3.55	0.719	2.05	0.184
340	5.45	2.00	3.78	0.806	2.18	0.206
360	5.77	2.22	4.0	0.898	2.31	0.229
380	6.09	2.46	4.22	0.993	2.44	0.253
400	6.41	2.72	4.44	1.09	2.57	0.279
420	6.74	2.98	4.66	1.20	2.7	0.308
440	7.06	3.26	4.89	1.31	2.83	0.338
460	7.38	3.55	5.11	1.42	2.96	0.369
480	7.7	3.85	5.33	1.54	3.08	0.402
500	8.02	4.16	5.55	1.66	3.21	0.424
550	8.82	4.98	6.11	1.99	3.53	0.507
600	9.62	5.88	6.66	2.34	3.85	0.597
650	10.4	6.87	7.22	2.73	4.17	0.694
700	11.2	7.93	7.77	3.13	4.49	0.797
750	12.0	9.05	8.33	3.57	4.81	0.907
800	12.8	10.22	8.88	4.03	5.13	1.02
850	13.6	11.5	9.44	4.53	5.45	1.15
900	14.4	12.9	9.99	5.05	5.77	1.27
950	15.2	14.3	10.5	5.60	6.09	1.41
1000	16.0	15.8	11.1	6.17	6.41	1.56
1100	17.6	19.0	12.2	7.41	7.05	1.87
1200	19.2	22.5	13.3	8.76	7.70	2.20
1300	20.8	26.3	14.4	10.2	8.34	2.56
1400	22.5	30.4	15.5	11.8	8.98	2.95
1500	24.1	34.8	16.7	13.5	9.62	3.37
1600	25.7	39.5	17.8	15.4	10.3	3.82
1700	27.3	44.5	18.9	17.3	10.9	4.29
1800	28.8	49.7	20.0	19.4	11.5	4.79
1900	30.5	55.2	21.1	21.6	12.2	5.31
2000	32.1	61.0	22.2	23.8	12.8	5.86
2200			24.4	28.8	14.1	7.02
2400			26.6	34.2	15.4	8.31
2600					16.7	9.70
2800					18.0	11.2
3000					19.2	12.8

Example - Water Flow through a Suction and Delivery Pipe

A pump delivers 120 gal/min. In a 4" pipe the velocity is 3.02 ft/s, in a 5" pipe the velocity is 1.92 ft/s, in a 6" pipe the velocity is 1.33 ft/s and in a 8" pipe the velocity is 0.77 ft/s

According recommended delivery velocity of water in steel pipes - a suitable delivery pipe is 6" with an approximately head loss of 0.1 ft/100 ft (from the table above).

According the recommended suction velocity of water in steel pipes - a suitable suction pipe is 8" with an approximately head loss of 0.03 ft/100 ft (from the table above).

As general rule of thumb - the suction pipe is a dimension above the delivery pipe.

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